After watching the fight again, aside from catching Henderson's kicks what else was Melendez doing to actually injure Henderson? He landed a few punches but was significantly out struck by the champ over and over again.

1) I've heard the "beat the champ" argument before, it's usually to justify a close decision in a title fight. Well look, IMO 2 men enter and the better fighter on that night deserves the win, their past victories should not enter into it. I can understand the champ keeping the belt in case of a clear decision draw. But I usually see this argument when there is mostly disagreement on who's the winner (instead of mostly agreement on a draw).

2) In kickboxing, the top competition has been the K1 annual WGP ladder tournament (now similiar with Glory). Titles don't enter into it.

3) In boxing, the top fighters walk around with belts (titles) as if they were trading cards. For example, Floyd Mayweather walks in the ring with 7 (or was it 9) belts, 3 of those are on the line. If the opponent also holds a few belts, then championship status loses it's meaning, it's just 2 great fighters now.

But yes, you can make the case for unified champions fighting an upcoming challenger.

That said, my curiosity has been piqued on the historic origin in boxing of "beat the champ". I've tried searching some, so far to no avail.

Yeah, I don't see any "sources" for this, but I know I've heard it many times in boxing circles. I've also heard it said by announcers during title fights. And not just one time, like every time I've watched a little fight for since some time in the 90s when I started watching boxing.

But no, I doubt you going to find a "source" for this, because it is an unwritten rule. Anyone who has never heard someone say, "In order to take the champs belt, you have to knock him out or win convincingly", has either not watched a title fight, or watched it with the sound turned off.

Undisputed championship - the champion who holds all the titles of the "major" sanctioning organizations

A Short History

The first lineal boxing champion on record is James Figg who became so in 1719. Until 1910, there was no organization that claimed to be an international governing body for boxing.

That means that some of the greatest champions in boxing history did not receive their championship by a sanctioning organization but by public acclamation.

Daniel Mendoza, John Jackson, and James Sullivan never carried belts because no organization gave them one. The first "official" belt on record is the Lonsdale Belt - and that is not a world championship belt.

In 1910, the IBU became the first organization that claimed to govern professional boxing on a worldwide scale. They later morphed into the EBU - a regional body that continues to this day.

In the 1920s, the NBA and the NYSAC established a rivalry, with both sanctioning organizations recognizing world championship.

The NBA became the WBA in 1962.

In 1963, the WBC sought to end the alphabet soup madness by inviting numerous national organizations under its umbrella. The EBU was one such organization that joined it.

NYSAC ceased recognition of world champions in the 1970s to focus solely on sanctioning fights in New York State.

There was a leadership dispute inside the WBA, so a bunch of members split and formed the IBF in 1983. The same thing happened again in 1988, and therefore the WBO was formed.

Hence the four "major" sanctioning bodies are:

WBC

WBA

IBF

WBO

The most major of the "minor" sanctioning bodies is the IBO which remains the only sanctioning body to institute computerized rankings.

In the 1970s, it was easy to become an undisputed champion. All you needed was to hold the WBC and WBA titles. From the 1980s-2006, you were considered an undisputed champion if you held the WBC, WBA, and IBF belts. In the late 2000s, the WBO was considered a "major" organization as well — so now you have to hold the WBC, WBA, IBF, and WBO belts to be the undisputed champion.

Naturally, there are no undisputed champions today.

The Lineal Championship

Traditionally, if you wanted to be the lineal champion, you had to beat The Man, and you had to do so clearly. Just who was The Man? The Man was the man who beat the man who beat the man.

What would happen in the event The Man retired before he got beat? The lineal championship would be up for grabs when the universally recognized #1 beat the universally recognized #2.

Now before we go trying to apply this tradition to modern boxing and modern MMA, there's some information we all need to know.

Traditionally, a fight wouldn't be stopped until there was a KO or one of the fighters was knocked down and couldn't beat the count. Hence, there were no limits on the amount of rounds that would be fought.

This is why when we look at fights from the Jack Johnson era, they would sometimes fight for 20-40 rounds. There was no scoring system.

Once they put a limit on the amount of rounds that could be fought, sanctioning bodies ruled that fights could be won by decision. The was decided simply with the referee raising the arm of who he thought won. This is still the practice in the UK, except for championship fights.

Obviously, with one man deciding the fight, decisions were often controversial, so efforts were underway to create some sort of scoring system that was judged by observers outside the ring.

At first, judges included the ref and two observers seated at ringside. Within the past 50 years, however, the referee no longer has the responsibilities of judging. That's placed in the hands of three judges placed at ringside.

The most commonly used scoring system right now is the 10-Point Must system - named as such because judged must award one fighter 10 points (before deductions for fouls).

I mention the evolution of boxing's rules because even though to gain the lineal championship, you had to beat the champion convincingly, that was true under a completely different set of rules.

Current lineal champions have to adhere to current rules, so the old tradition does not apply.

For the record, there's only 5 lineal champions in boxing today. They are:

Akira Yaegashi (Flyweight)

Guillermo Rigondeaux (Super Bantamweight)

Sergio Martinez (Middleweight)

Andre Ward (Super Middleweight)

Chad Dawson (Light Heavyweight)

All these lineal champions became so convincingly — so even if the old tradition does not apply, their championships adhered to the spirit of the old tradition.

Alphabet organization championship
The alphabet organizations are the ones who award belts — and frankly, anyone can create an alphabet organization. There's highly-regarded organizations (like the IBF) and lightly-regarded organizations (like the WBU).

The only requirement for being recognized as a champion by an alphabet organization is that they recognize you as such. In fact, you don't even have to win a fight. Sometimes they'll just award them to fighters.

The other side of the coin, of course, is that they'll often remove their recognition of a world champion if the world champion does not pay the required sanctioning fee. This is one major reason why alphabet championships are often "vacated".

Under the system of the alphabet organizations, you definitely don't need to beat the champion to become the champion.

Undisputed championship

In the 80s, the term "undisputed champion" became something to strive for because the thought was that if you were universally recognized as champion by all major sanctioning bodies, you must be legit.

Of course, the problem with this is that the major organizations increased from 2 to 4 sanctioning bodies in the course of 30 years.

Yet another problem was that the alphabet organizations could remove their recognition of a champion for any reason whatsoever. In fact, Graciano Rocchigiani sued the WBC for removing him from championship recognition for reasons that contravened their own rules. The courts ruled in Rocchigiani's favour — awarding him $30 million.

Further casting doubts upon the "undisputed championship" legitimacy was something that happened during Lennox Lewis' undisputed championship reign. Don King paid Lennox Lewis $1 million to vacate his IBF title. Lewis accepted the money, did as King asked — and Lewis was no longer the undisputed champion.

Conclusion

Traditionally, to be a champion in boxing you had to beat the champion without controversy. This was because the only championship that matter was the lineal championship. Before the advent of sanctioning organizations, fights were not won by decision.